Base plate for frogs and crossings



July 29, 1947. T. w. sTEDMAN l BASE PLATE FOR FROGS AND CRSSINGS v Filed Aug. 26, 1943 1 5 w l mn 1. .I L d M i p .vw/ 1 Eb 2 l 1 n.5 t H U I d g 4 \w fr 1 ,5.@ a mw l lnlV. fr HU M lH E M.. Y m n w f m .b :la .nM

rwe/wbov THEODORE VV. STEDMAN Patented July 29, 1947 UNITED STATES y `2,424,916 I BASE PLATE Fon FRoGsAND oRossING's Theodore W. Stedman, New York, Nr'Y., assignor to The Firestone Tire & 'Rubber Company, Akron, Ohio, a corporation of 0ho Application August ze, 19'4'3, serial No. 500,145V e l 4. This invention relates to Abase plates for'the frogs and crossings of railroad trackways, Aand more especially it relates to base plates 'of ythe character mentioned adapted resiliently to vsupport frogs and crossings in their entirety. Frogs and other special types vof railywayv track construction, such as crossings, lare `subject to especially hard wear, yet require to be `extreniely durable since they must have a high factor of safety because of the hazards involved incase of failure. In order to improve the wearingmqualities of frogs and crossings, the elements thereof that are subject to greatest wear are made. of special hardened steels, which greatly adds to the,` cost. The wear upon frogs and crossings is" caused by the impact load of heavy locomotives and other rolling stock moving thereover, and it is the common practice of most railway vcompanics to mount frogs and crossings upon heavy@ steel plates of approximately 3A inch thickness `for 2 the purpose of equalizing and distributing the impact load.

To compensate, in part 'at least, for` the rigidity of the structural units, efforts have been inadetoq.

cushion the units and thus reduce 4asmuch as 25 respective ties and the steel base plate of aunitffa In other cases, rubber pads coextensive in area with the metal base plates have been interposed between the latter and the ties. Neither of these expedients has been entirely satisfactory since the only cushioning contact has been immediately-0 above the individual ties;

The chief objects of the invention are to provide an improved base plate for frogs and ycrossing units that will cushion the same; that will mantain the original unified rigidity of the units; 45`

and that will enable the units to deflect uniformly With an equal distribution of the load throughout their structures. More specifically the invention aims to reduce the maintenance expensesof frogs ported. `Other objects Will be manifestes .the

description proceeds. 'l

l. Of the accompanying drawing:

Fig. 1 is a plan View of a railway frog,

plate embodying the invention operatively 'asso-vv .55`

a plurality` ofgdeterminately arranged apertures ciated therewith, and ties upon which thebase plate is mounted and secured;

Fig. 2 is a plan view, on a larger scale, of the improved base plate;

Fig. 3 is an edge view of the improved base 60 1 claim. (ci.

plate; a part thereof being sectioned on line 3-3 lline 4-44 of Fig; 1.

1 Y Referring nowto Fig. 1 of the drawing, there is shown an improved base plate that is desigfnated as a whole'by the numeral I0, said base plate being secured to railroad ties II by' lag screws I2, I2, and supporting on its upper face a rail frog I3 The latter is secured to the base plateV I0 by ra plurality of cleats I4 that are removably attachedto the base plate by bolts I5.

The area and proportions of the base plate will vary according to the particular frog or crossing with'which it is designed'for use, said frogs com- Y prising several different types.

As is clearly shown in Fig. 3, the base plate I0 "is a composite, laminated structure composed of resilient elements and rigid elements. More specifically, there are three resilient elements and two rigid elements, each of the latter having a resilient element on each side thereof. The rigid elements, designated I'I, I1, are of substantially identical structure, each consisting of a steel plate of `a` quality `known as medium carbon. l yThese plates may be relatively thin as compared .-to 4:the thickness of all-metal base plates heretofore employed, a thickness of 3/16 inch being found sucient in most cases. Interposed between the metal plates I'I is a layer I8 of resilient rubber composition of relatively high modulus, said layer being permanently bonded to the confronting `faces-of .the `metal plates I 'I by vulcanization.

The layerIB is relatively soft (about 35 durome- 6 ter hardness) `and in the illustrated embodiment ofthe invention is of 1A; inch thickness.

vulcanized to the opposite face of one of the 4metalplates `I'I is a layer 20 of rubber composi .tion of medium modulus. The layer 20 is about 50 durometer hardness and thus is not as soft as the intermediate rubber layer I8. Also it is thinner --than thelatter, being but 1A; inchthickness. The 1 layer-20 constitutes the bottom layer of the base plate II)v when the plate is in use as shown in Fig.

. 1, ysaid layer 2n, then restingin contact with the 'ties II. Vulcanized to the opposite face of the other .metal plate I'I Vis a layer 2| of a synthetic rubber-like material which may be the material Y known as neoprene (a polychloroprene) and crossings, and the ties Von which they are sup-I 50,

The V layerl I, whichconstitutes the top facing of the :composite base plate, is of the same thickness as the bottom layer 20. It is of high modulus (about Y 73 durometer hardness) and therefore is stiffer than'the other resilient elements of the structure. vIn the manufacture of the improved base plate '24, 24 are formed therein, said apertures being square in plan, of larger area in th'e bottom face of the plate than in the top face thereof, and of stepped formation between the said top and bottom faces. The apertures 24 constitute seats or sockets for metal inserts 25 that have exterior lateral 'faces shaped complementarytothe :shape of said apertures. =Each insert 25'1has .an axial aperture 26 therein, which' aperture is tapered toward the smaller end of the insert, said aperture being spare at the smallendof A.theinsert and circular at the larger end thereof. 'The bolts I that secure the cleatszldntothebasezplate I0 have tapered heads that arefreeeivable lin the tapered apertures in the inserts 25. The 7inserts 25 are mounted in the apertures 214 of the base plate and bonded thereto by vulcanization at the time the base plate is vulcanized.

The base plate I0 also is provided with a plurality of circular apertures 28, 28 :for receiving the lag screws I2 by which the base :plate iis secured tothe ties 1I I. The apertures :28 are formed by drilling, and this preferablyfis done .by ythe customer ywho `will drill Vthe -same iin :accordance 4with the'spacing` of Ythe'ties I-I,such `spacing-differing yin various frog -and `crossing installations. The -`arrangementl is lsuch that 'the fplates 'II .do

ynot move lin `theirown Yplanes .relatively of feach other or Vrelatively of the ties `or the frog -or crossing, :any ymovement of said plates '.b'eing -very slight, and normal to itheir planes. Furthermore, the'composite base plate supports ithe entirefrog or crossing -structure, thus substantially .preventing relative movement between fthe various Lelements of said structure, equalizing=andidistribut ing `impact `load thereon, `.arrdmbviating .wear `and shearing strains. The arrangementalsofobvates fthe .imposition Lvof shearing fstrains ion .the :nonmetallic :components of ethe base xplate.

Although fonly neoprene is mentioned .as 'the icomposition of theftop facingiz I i .of therbaseiplata "ittisinot intended that the invention bezlirnitedto this particular rmaterial, but .that lnotifier:synthetic rubber-like .compositions .having sonre :or #all -of thephysicalzand chemical characteristics ofineokprenemay `be 'substituted in lieuth'ereof. "Among `such characteristics mayabenn'entionedthezability to resist-the deterioratingfeflectof oil l'and grease, .good aging `qualitiesupon Sexposure to th'e Lelements, fand .resistance t'o the `charring effect 'of Vhot cin'ders. `Among 'synthetic .compositions that may be 'substituted for neoprene lare lth'e 4.plasltics known lby `'the tradeiname Aof funaffor 'example, fBunaS Ita copolymer of 'butadiene and styrene) Since .the `composition 'of .fthe .top `=layer `2I is relatively stiff, l-it doesfnotreadily "flow and 4is not excessively deformed :and displacedbyithe weight of the frog I3-'thatrests upon-localrreg'ions thereof.

The soft, relatively thick intermediateres'ilient layer `I 8 absorbs most 'of the deflection o"f fthe upper plate VI when th'elatter is -Lsbjected to strain and ijolts arising from fthe limpact Vo'f 4'car lwheels passing overrthe frog I3, Thusbutlittle yof suchstrain is imparted tofthelower plate =I"I, and `such strain that is imparted 'thereto 'is 'distributed uniformly thereover. `vItfis for Ythisreason that'the combined thicknessof ithe-two -met-al plates i'II -is less than the thickness 'of the Isingle' metal plates Iheretofore employed, with resulting A economy of material. Moreover f'there is 1but little impact Etrans'lated -'to -the 'ties II `lvswitl'l the result that much -wear onthe latter Iis eavoided. This is especially advantageous 4in #street railway -trackage -where-the'rties farelenibed'dedlin'theconcrete base of a pavement, and replacement of Worn ties is difficult and time-consuming. The 'bottom resilient layer 20 of rubber composition lpreventsfriction of the `metal of the base plate upon the ties and contributes to the prevention of Wear upon the latter. Since the composition of .this layer is of medium stiffness, it is not eX- tensively deformed or displaced by local contact -Withth'e ties I I.

Theinvention provides an improved base plate fthatireduces wear on frogs, crossings, and ties of railway .trackage that conserves metal, that reduces noise, and'which achieves the other advantages set out in the foregoing statement of objects.

Modication may be resorted to without departing,from Athe-spirit of the invention, or the Ascope thereof as denedrby the appended claim, .and -the -various dimensions set forth and the specific durometer hardness data are not em -ployedina .limiting sense, but only as illustrative vexamples ofthe characteristics of one embodi- .mentof the invention.

What is .claimed is:

Ina base plate of the character described, the .combination of a Vpair of metal plates disposed one vover the other in parallel relation, layers of resilient material coextensve with said plates disposed between them and on the vtop .and bot- ;tom faces of the composite structure, said material being lbonded to said plates, and metal linserts within and extending through the composite structure, each of said inserts being formed lwith an axial bore Yadapted to receive the head o'f a bolt by `which a frog or 'crossing is secured to'thelbase plate, said inserts being polygonal in transverse section and received Within rcspective apertures of complemental shape in the base plate so asto be restrained .against rotary move-- 'Inent'relatively of the base plate when the bolts 'aretightened, each of said inserts being larger exteriorly .at its `lower end than at its top, and Ihaving its krespective sides of stepped formation., thus `providing surfaces that are 'parallel to the Haxis o'f the insert, thereby enabling the metal plates to have limited `movement relatively of "each'otherand of the inserts ina direction noi*- in'iallto their planes, yet restraining such relative lso lmovementof the plates in the direction parallel toftheir planes.

THEODORE W. STEDMAN.

REFERENCES CTElD The following references are of record in the file of this patent:

UNITED STATES PATENTS :Number Name Date 2,279,110 'Collins Apr. 7, 1942 "2,146,341 IKahn Feb. 7, 1939 1,8922943 Geyer Jan. 3, 1933 T2,371,927 Schmidt et al Mar. 20, 1945 '38'1U56 Cumming Apr. 10, 1888 872,473 Strong Dec. 3, 1907 1;'4285573 Alexander Jan. 20, 1925 31,792,620 Wells Feb. l7, 1931 2,155,155 Stedman Apr. 18, 1939 2,167,716 Harkins Aug. 1, 1939 E896,154 Reinoehliet'al Aug. 18, 1908 21,972,825 Funston Sept. 4, 1934 877,064 'Schultz Sept. 13, 1932 

